Captain Rex has the standard Clone Trooper leg piece- white legs with a black leg joint, and also has the same printing design on the torso piece as most Clone Troopers in The Clone Warssubtheme, however the arms are blue instead of white. Rex's headpiece is unique with five o'clock shadow and a scar under his lower lip in addition to the standard The Clone Wars Clone Trooper face print.
Captain Rex wears a white clone trooper helmet, with blue stripes above the visor and one stripe running vertically across the faceplate. Also printed are blue lines near the top of the helmet, resembling Jaig eyes, an award earned by Rex in the Star Wars universe, along with grey printing at the bottom of the helmet's crest, yellow dashes above the visor, and the standard clone helmet printing. Rex comes equipped with two grey Commando pistols, a grey pauldron and kama, a grey rangefinder, which can also be switched for a visor or floodlights.

Phase II Variant

In 2013, Rex was redesigned, and is based on his Phase II armour. His helmet is a new mould, larger than his old one. It has two large, tube-like breath filters at its base and the crest on top is rounded instead of straight. The visor printing is similar to his old helmet's, with the T-visor lined with blue and Jaig eyes above it. Two brown lines, one on each side, run from his visor to the base of the helmet. Tally marks are present on the sides of his helmet.

Rex's new pauldron is made of cloth. It's black with several large blue printings covering his left shoulder. The top of his torso has printing of the pauldron underneath where the cloth piece lies. It has three ammo cartridges on the dirt-spattered armour as well. The back has a belt with a cylindrical thermal detonator printed on along with a rectangular panel with several dots and lines inside. Grime printing is also present here. Rex has blue arms and black hands. He has the same head as his Phase I minifigure but with some minor changes.

The kama is also cloth, this one black and unprinted. It is identical to the ARC trooper battle pack released in 2012. His hips are black and the legs white with printing of blue kneepads and tally marks.

Captain Rex appeared as a playable character in the video game LEGO Star Wars III: The Clone Wars. Rex's appearance in the game is much like his physical minifigure's, and is armed with two commando pistols. Rex has the ability to single jump, throw EMP grenades and plant bombs in specified Clone Trooper areas. Captain Rex can also command squads of Clone Troopers on battlefields, and in some dark areas, he automatically lights up areas with floodlights that he attaches to his helmet.

CT-7567, nicknamed Rex, was a Clone Trooper Captain in the Grand Army of the Republic. Throughout the Clone Wars, Rex was in command of Torrent Company, a unit within the 501st Legion. At some point, Rex was awarded Jaig Eyes. Rex worked closely with Jedi General Anakin Skywalker and Jedi Commander Ahsoka Tano, both of whom he assisted on several missions including battles on Christophsis, Orto Plutonia, Ryloth, Teth, Geonosis and Lola Sayu. He was also known to work with Clone Marshal Commander Cody on many occasions since Skywalker also commonly worked with High General Obi-Wan Kenobi.